TWI443449B - Photomask - Google Patents

Description

Mask

The present invention relates to a reticle, and more particularly to a reticle for improving image quality for problems caused by lens aberration under extreme illumination.

Recently, the semiconductor industry has tended to reduce the design and development of circuit components, and one of the most important steps in the entire semiconductor process is photolithography. All the patterns related to the structure of semiconductor components, such as the film of each layer, are determined by the lithography process to determine the size of the critical dimension (CD), which is also determined by the development of lithography process technology. Therefore, the accuracy of the transfer of the mask pattern plays a very important role. If the pattern is transferred incorrectly, it will affect the tolerance of the critical dimensions on the wafer and reduce the resolution of the exposure.

However, when the light passes through the scanner, after the lens absorbs the light energy, the lens will be unevenly heated due to the uneven distribution of the diffraction pattern, so the image will be deformed by the lens aberration, thereby reducing the image. Imaging quality. The above problems are more pronounced when lighting uses strong off-axis illumination (OAI), such as dipole illuminators.

The present invention provides a photomask which can effectively improve the deterioration of image quality caused by lens aberration.

The invention provides a photomask suitable for a lithography machine, and the reticle comprises a substrate and a reticle pattern disposed on the substrate. The reticle pattern includes at least one main pattern and a plurality of sub-resolution assistant features (SRAF). The sub-analytical auxiliary patterns are disposed apart from each other around the main pattern, wherein a distance between each of the sub-analytical auxiliary patterns and the main pattern is about 3 to 10 times a line width of the main pattern.

According to an embodiment of the present invention, in the photomask described above, the line width of the sub-analytical auxiliary pattern is, for example, about 1/4 to 1/10 times the line width of the main pattern.

According to an embodiment of the invention, in the photomask described above, the line width of the sub-analytical auxiliary pattern is, for example, about 1/4 to 1/5 times the line width of the main pattern.

According to an embodiment of the invention, in the photomask described above, the distance between adjacent two sub-analytical auxiliary patterns is, for example, about 5 to 10 times the line width of each sub-analytical auxiliary pattern.

According to an embodiment of the invention, in the reticle described above, when the reticle pattern includes a plurality of main patterns, the secondary analytic auxiliary pattern is, for example, located between two adjacent main patterns.

According to an embodiment of the invention, in the reticle described above, the secondary analysis auxiliary pattern is, for example, located at a central position between adjacent two main patterns.

According to an embodiment of the invention, in the photomask described above, the main patterns are arranged, for example, in an array.

According to an embodiment of the invention, in the reticle described above, the secondary analysis auxiliary patterns are arranged, for example, in an array manner.

According to an embodiment of the invention, in the reticle, the reticle pattern is, for example, a light-transmitting region or a partially light-transmitting region on the substrate.

According to an embodiment of the invention, in the reticle described above, the area other than the reticle pattern is, for example, an opaque area on the substrate.

Based on the above, in the reticle of the present invention, a plurality of sub-analytical auxiliary patterns are disposed around at least one main pattern, and a distance between the sub-analytical auxiliary pattern and the main pattern is about a line width of the main pattern. 3 to 10 times, the diffraction pattern can be more evenly distributed, so that the lens can be uniformly thermally expanded, so that the image obtained on the wafer has better image quality. It is worth noting that the secondary resolution auxiliary pattern does not affect the original optical system resolution. That is, the secondary analysis auxiliary pattern does not affect the image normalized image log slope (NILS) without considering the lens aberration.

In order to make the above-described features of the present invention more comprehensible, the following detailed description of the embodiments will be described in detail below.

FIG. 1 is a schematic view of a photomask according to an embodiment of the present invention. 2 to 4 are schematic views of a photomask according to another embodiment of the present invention.

Referring to FIG. 1 , the reticle 100 is applied to a lithography machine, and the reticle 100 includes a substrate 102 and a reticle pattern 104 disposed on the substrate 102 . The reticle pattern 104 is, for example, a light-transmitting region or a partially light-transmitting region on the substrate 102. The area other than the mask pattern 104 is, for example, an opaque area on the substrate 102.

The reticle pattern 104 includes at least one main pattern 106 and a plurality of sub-analytical auxiliary patterns 108. The line width W1 of the main pattern 106 is, for example, 100 nm or less, and the shape of the main pattern 106 is, for example, a strip shape, but is not intended to limit the present invention. Moreover, the line widths and shapes of these main patterns 106 may be the same or different from each other. According to the technical knowledge, the line width and shape of each main pattern 106 can be adjusted according to actual design requirements.

The plurality of secondary analysis auxiliary patterns 108 are disposed apart from each other around the single main pattern 106, and the distance D1 between each of the secondary analysis auxiliary patterns 108 and the main pattern 106 is about 3 to 10 times the line width W1 of the main pattern 106. It helps to improve the uniformity of the diffraction pattern. The secondary analysis auxiliary pattern 108 may be a nano-sized, a size flexible, an arbitrary shape, or a secondary analysis auxiliary pattern that does not affect the normalized logarithmic slope (non-NILS-impacted).

The line width W2 of the secondary analysis auxiliary pattern 108 is a line width that makes the secondary analysis auxiliary pattern 108 unimageable. The line width W2 of the secondary analysis auxiliary pattern 108 is, for example, about 1/4 to 1/10 times the line width W1 of the main pattern 106, and the line width W2 of the secondary analysis auxiliary pattern 108 is more the line width W1 of the main pattern 106. About 1/4 times to 1/5 times. In this embodiment, although the pattern of the secondary analysis auxiliary pattern 108 is illustrated by taking a rectangular shape as an example, it is not intended to limit the present invention. In addition, the line widths and shapes of the secondary analysis auxiliary patterns 108 may be the same or different from each other. According to the technical knowledge, the line width and shape of each secondary analysis auxiliary pattern 108 can be adjusted according to actual design requirements.

The distance D2 between the adjacent two sub-analytical auxiliary patterns 108 is, for example, about 5 to 10 times the line width W2 of the sub-analytical auxiliary pattern 108, and the uniformity of the diffraction pattern can be further improved.

The plurality of secondary analysis auxiliary patterns 108 may be disposed on the same side, both sides of the single main pattern 106 or around the main pattern 106. In addition, the secondary analysis auxiliary pattern 108 may also be located between the adjacent two main patterns 106, such as a central position between the adjacent two main patterns 106, at which time no additional marking space (reticle) needs to be designed on the reticle. Space) to correct the imaging pattern, so it does not affect the original use space of the reticle 100.

In this embodiment, although the number of main patterns 106 is exemplified by four, and the number of sub-analytical auxiliary patterns 108 is illustrated by 30, and the main pattern 106 and the sub-analytical auxiliary pattern 108 are The array arrangement is described as an example, but is not intended to limit the present invention. As long as two or more secondary analysis auxiliary patterns 108 are disposed around one main pattern 106, which belongs to the scope protected by the present invention, the number of primary patterns 106 and secondary analysis assistance can be assisted by those skilled in the art according to design requirements. The number of patterns 108 and the arrangement thereof are adjusted.

For example, referring to FIG. 2 and FIG. 4 , the number of the secondary analysis auxiliary patterns 108 located on both sides of the main pattern 106 may be different from each other, and the secondary analysis auxiliary patterns 108 may not be arranged in an array manner. Referring to FIG. 3, the shapes of the main patterns 106 may be different from each other, and the main patterns 106 may not be arranged in an array manner. In addition, referring to FIG. 4, the secondary analysis auxiliary pattern 108 is different from the rectangular shape in FIG. 1 to FIG. 3, and the secondary analysis auxiliary pattern 108 may be a diamond shape in FIG.

According to the above embodiment, since the plurality of secondary analysis auxiliary patterns 108 are provided around the at least one main pattern 106, and the distance D1 between the secondary analysis auxiliary patterns 108 and the main patterns 106 is about the line width W1 of the main patterns 106. 3 to 10 times, the diffraction pattern can be more evenly distributed, so that the lens can be uniformly thermally expanded, so that the image obtained on the wafer has better image quality.

Further, since the distance D1 between the secondary analysis auxiliary pattern 108 and the main pattern 106 is controlled within about 3 to 10 times the line width W1 of the main pattern 106, it is not necessary to design an additional line space on the reticle 100. The imaging pattern is corrected so that the original use space of the reticle 100 is not affected.

In summary, the above embodiment has at least the following features:

1. The reticle of the above embodiment produces better image quality on the wafer.

2. When the reticle of the above embodiment is used, the original use space of the reticle is not affected.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

100. . . Mask

102. . . Substrate

104. . . Mask pattern

106. . . Main pattern

108. . . Secondary analysis auxiliary pattern

D1, D2. . . distance

W1, W2. . . Line width

FIG. 1 is a schematic view of a photomask according to an embodiment of the present invention.

2 to 4 are schematic views of a photomask according to another embodiment of the present invention.

100. . . Mask

102. . . Substrate

104. . . Mask pattern

106. . . Main pattern

108. . . Secondary analysis auxiliary pattern

D1, D2. . . distance

W1, W2. . . Line width

Claims (10)

A reticle is applicable to a lithography machine, and the reticle comprises a substrate and a reticle pattern disposed on the substrate, the reticle pattern comprising: at least one main pattern; and a plurality of sub-analytical auxiliary patterns ( The sub-resolution assistant feature (SRAF) is disposed apart from each other around the main pattern, wherein a distance between each of the sub-analytical auxiliary patterns and the main pattern is 3 to 10 times a line width of the main pattern. The reticle of claim 1, wherein a line width of each of the analytic auxiliary patterns is 1/4 to 1/10 times a line width of the main pattern. The reticle of claim 2, wherein a line width of each of the analytic auxiliary patterns is 1/4 to 1/5 times a line width of the main pattern. The photomask of claim 1, wherein a distance between adjacent two sub-analytical auxiliary patterns is 5 to 10 times a line width of each of the sub-analytical auxiliary patterns. The reticle of claim 1, wherein when the reticle pattern comprises a plurality of main patterns, the sub-resolution auxiliary patterns are located between adjacent two main patterns. The reticle of claim 5, wherein the secondary analytic auxiliary patterns are located at a central position between adjacent two main patterns. The reticle of claim 5, wherein the main patterns are arranged in an array. The reticle of claim 5, wherein the sub-analytical auxiliary patterns are arranged in an array. The reticle of claim 1, wherein the reticle pattern is a light transmissive area or a partially transparent area on the substrate. The reticle of claim 1, wherein the area other than the reticle pattern is an opaque area on the substrate.